Description
By design, shared mailboxes in Shield are treated differently from licensed user mailboxes. This article highlights how protection levels and risk levels work with shared mailboxes to determine message delivery locations.
Shared Mailboxes and Trust Networks
Shared mailboxes do not use the Trust Network to make delivery decisions. Although the X-ray of a message or the contact trust decision might state that a sender was trusted or silenced, this information is disregarded, and only risk levels will inform the delivery location of a message.
Because a shared mailbox in Microsoft 365 does not have a password, users cannot sign in to Shield to change its preferences. Shield Admins must make any preference changes to the shared mailbox in Shield.
Risk Levels, Protection Levels, and Message Delivery Location
Risk Levels
By default, shared mailboxes use the Organization's risk levels. Shared mailbox messages will follow this pattern of assessed risk:
- High: emails are held in Shield's Jail, outside the mailbox.
- Moderate: emails are sent to the Junk folder.
- Low: emails are sent to the Junk folder because the contact's trust network decision is not considered in the delivery decision.
- None: emails are delivered to the Inbox.
Only Shield Admins can view preferences for a shared mailbox to make changes to Risk Levels.
Protection Levels
Shield Protection Levels determine how risk levels affect message delivery. Protection levels for shared mailboxes work as follows:
- Maximum: Low, moderate, and high risk levels are applied as listed above to all messages.
- Minimum: Only messages determined to have a high risk level will be filtered.
- Passthrough: Risk levels are not applied to any messages.
By default, a shared mailbox is configured to Minimum protection, which only performs actions on messages with high risk levels.
Only Shield Admins can view preferences for a shared mailbox to make changes to Protection Levels.
How Protection Levels and Risk Level Changes Affect Shared Mailbox Delivery Location Decisions
| Protection Level | Delivery Decision |
| Maximum | Moving a risk setting to none will result in more mail being delivered to the shared mailbox. Maximum security protection is not the default setting, but a Shield Admin can update the shared mailbox to maximum security if needed. |
| Minimum | Moving a risk setting to high risk will result in less mail being delivered to the shared mailbox. This is the default setting. |
| Passthrough | Moving a risk setting to high risk will have no effect on delivery. |
Getting Help
If you need assistance with shared mailboxes in Shield, please contact the Partner Success team.
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